Coating composition



- Reissued Feb. 22, i

v .airao s'm'riez's PATENT; OFFICE COATING fifiOSITION I I wasaeaassmsia ssss:

vanla Industrial Chemical Corporation, a corporation of Pennsylvania NoDrawing. Original No. $319,389, dated May 18, 1943, swarm. 345,860, July16, 1940. ap- .plication for reissue August 9, 1943, Serial No.

This invention relates to a thermoplastic coating composition purposedparticularly as a coating for paper and other fibrous orcellulosicmaterials. such as cloth of different sorts.

Heretofore the substances preponderantly used for coating paper havebeen paraffin wax and one or more of the more expensive types of resin,

such as coating compositions containing vinyl resins or the polymers ofacrylic acid esters.

Paraflln wax is the typical paper coating material, but of itself doesnot give to a maximum all the desired qualities of a paper coating, inthat it tends to opacity, is of relatively low melting point, and'haslow resistance to abrasion.

'bocyclic terpene hydrocarbons are, without hydrogenation or othertreatment,-highly compatible with paraifln wax to such extent that theyblend in all proportions with the wax without granulation in the mixtureor separation between 5 Claims. (Cl. 26028) cluded in the composition insufliciently great proportion, we have also discovered that paper coatedwith the mixture is translucent and in practical effect transparent, andthat it possesses a glossy finish so that the coated paper is suitablefor use in display packages for foods and other materials.

. The proportions'in which terpene resins, even those of the highestmelting point which have been made, are compatible with paraffin wax areunlimited, so that there may be included in thewax mixture any relativeproportions which are desirable or economical in making a compositionfor use in making any specialized type of coated paper or fabric. Inthis connection it should be emphasized that the terpene resins requireno addition or modification in order that they may possess such broadmeasure of compatibility with the paraflin wax.

In line with the foregoing, we may make a paper-coating compositioncontaining, for example. 90% paraffin wax, and 10% of high-meltingterpene resin. Such composition has good heatsealing properties, inwhich the parailln wax is of itself deficient, and has a higher glossand lesser opacity than paraflin wax. We have found that even thisrelatively small proportional inclusion of terpene resin, and this isparticularly true the wax and resin.. Thus, we have discovered.

that we are able successfully to blend with par-. afiin wax the highestmelting terpene resins which may be made by polymerizing selectedunsaturated constituents of gum spirits of turpentine and other terpenestarting materials; such as those high polymers of beta-pinene, andterpene mixtures in which beta-pinene preponderates, which are disclosedin the application of Samuel G. Burroughs, Serial No. 288,390, filedAugust 4, 1939, issued December 7, 1943, as Patent No. 2,355,912. Wehavefound that by so doing, we are able to produce with paraflln wax .ahomogeneous mixture having a melting pointmuch higher than that oi theparailln wax, and

yet WhichFpoSsesses wax characteristics. Such if the resin has a highmelting point such as a melting point of from 250 F. upward, gives acoating composition which, when applied, has better fllrn continuity andbetter resistance to abrasion than unmodified paraflin wax.

As exemplary of coating compositions capable of rendering papertransparent and giving it a glossy finish, so that it is well suited forthe packaging of foods and the like. we may mix paraflin wax andhigh-melting terpene resin, such as aterpene resin melting about 275 F.,in a proportion of from 30% and more of the resin.

A coating composition in which the brittleness of the resin is modifiedby an addition of wax may be made by mixing the resin with 25% or' evenless of paraffin wax. Such composition is useful for glazing paper forpurposes in which great transparency or translucency is of primaryimportance.

In all mixtures of thewax and resin the qualiablend of terpene resin andparafiln Waxes, in

accordance. with the proportional inclusion. of

- the resin and its melting point, has a greater resistance to abrasionthan paramn wax, and has better heat-sealing properties than the waxtaken by itself. If a terpene resin mixed with the wax is ofsufilciently high melting point and is inties imparted to the mixture bythe resin are more striking for any proportional inclusion of the'resin,.the higher the melting point of the resin which is included.

In addition to paraffin waxall the other wax- I like materials, whetheror no they be wholly hydrocarbon in nature, are compatible with ter- 2pene resin of all melting points. Thus, for example, in ourthermoplastic coating composition we have made homogeneous mixtures ofterpene resin having melting-points up to the highest currentlyobtainable with ceresin wax', candelilla wax, camauba wax, montan wax,Japan wax: and synthetic waxes, such as those produced by theesteriflcation of long chain alcohols with fatty acids, and hydrogenatedfats and oils;

Most of the other wax-like materials lack the chemical resistance ofparaflin wax, but otherwise have properties making them useful in athermoplastic coating composition of the sort with which we areconcerned. i

Among the wax-like materials which we may use, parafiln wax may beconsidered the preferred waxy ingredient, both for reasons of economy,and because its other properties, such as light color,chemicalresistance, and relatively high melting point render itsuitable. It is the wax typically usedfor paper coating, and, in

known thermoplastic coating compositions for paper coating and likeuses. The usual high grade of ,paraihn waxobtained from petroleum oilsmelts at about 140 F. Certain other waxlike materials, typicallycarnauba wax, melt at relatively high temperatures. 4

In our coating composition leis important that the terpene resin behigher melting than the wax -like material with which it is mixed,.inorder that the more substantial advantages coming from its inclusion maybe had. This is true with whatever one, or more of the wax-likematerials itmay be'mixed. It follows that, in order to obtaincompositions having properties best suited to particular materials to becoated, and particular uses to which'the materials thus coated are to beput, we vary the melting point of the terpene resin and itsproportionalinclusion in accordance with the melting temperature of thewaxlike material for any intended use of the composition. .It is roughlytrue that inclusion of the terpene resin in any proportion with awax-like material proportionally modifleslthe properties of thatmaterial, and inclusion of a wax-like matev rial in any proportion witha terpene resin proportionallymodifles the properties of the resin.

, Because of the compatibility of the highest melting terpene resin withall wax-like materials, and because there is nothing critical about theproportional inclusion of the ingredients of the composition, it is asimple matter to apportion the ingredients of the composition inaccordance with their melting properties and the intended use of thecomposition. Thus, we may give, as roughly illustrative, a coatingcomposition for a coated paper of good heat-sealing propertiesconsistingessenti'ally of about 90% paraflin waif 'melting at about 140"F. and about 10% -of tor-.-

pene resin melting at about 300 F. As a composition for glazed paper foruse in display packages and the like, we may give as roughly exemplary acomposition consisting essentially. of about40%- paraflln wax melting'atabout 140- F. and about 60% of terpene resin melting at'about 250! PL,For a composition having primarily the properties of a plasticizedresin, we may give as roughly exemplary one consisting essentially ofabout parailin wax melting at about 140 F.

r and about 75% of terpene resin melting at about 275 F. It is a simplematter to obtain varied desired properties of the coating composition byvarying the proportions of the ingredients and by selectingtho-ingredients on'the basisoftbeir melting temperatures. By referenceto the melting temperatures of all the various other waxlike materials,it is also a simple matter to make up from the other wax-like materialsand terpene resin coating compositions which parallel the paraiiin-waxcompositions in the properties dependent upon the meltingcharacteristics of the ingredients.

All variants-oi the terpene-containing coating composition abovedescribed are thermoplastic compositions, and by this we mean that inapplying them they are caused to flow by heat. They thus may be preparedfor application, and may be applied by any procedure known to besuitable for the application of coatings of paraffin-wax and otherwax-like materials, or coating compositions consisting essentially ofsuch materials and ingredients other than terpene resins. The mixture ofthe ingredients is made by fusing them together, and may be appliedeither as made or by refusing the mixture.

its intimate association with the wax-like material, or materials withwhich it is mixed. It may be applied to paper or fabric in any of thewellknown methods by which they have been coated; as by immersion,hot-spraying, use of the doctor knife, or working in hot rolls. It maybe applied to the surfaces of more substantial bodies, in any way knownto be suitable for applying thermoplastic coatings; as by immersion orhot-spraying.

Our coating composition, consisting essentially of an unaltered andrelatively inexpensive terpene resin and a wax-like material, which maybe the relatively inexpensive paraflin wax, thus has commercialadvantage over coating compositions 01 similar sort whichlnclude withthe wax in ying ingredients of some more expensive It has, in comparisonwith the wax alone, greater resistance to abrasion, better heat -sealingprop erties due to the inherent tendency of the resin to act as athermoplastic adhesive, gloss and transparency in higher order, and theability to'im- I prove, the capacity of paper coatedwith it to receive asuitable printing ink without blurring Other advantageous qualities ofour coating I composition are attributable to the wholly hydrocarbonnature of its terpene resin content. For

1 other reagents.

' under.

example, that resin tends to impart to the coating composition its owninherent qualities of chemical resistance to acids, alkalis, salts; and

It also tends to-impart tothe coating composition in which it isincluded re-. sistance to enzyme reactions,'and thus to'render paper orfabric coated with it suitable for use in packaging foods. If, as isusual, we include the terpene resin with paraiiin wax, which is alsowholly hydrocarbon in nature, the coating composition possesses thosequalities in maximum To our base coating composition, co tingessentially of a wax-like material and a highermelting terpene resin,other ingredients for imparting specific additional qualities may beadded;

Thus, a number of high molecular weight strength-increasing substancesare compatible both with the paraflln wax, or otherwax-like material,and with the terpene resin. For example,

we may add to the composition a minor pr portion of strength-increasingsubstances, such as the polymers of isobutylene, thelower polymer izedforms of the higher-esters of acrylic acid,

such as butyl-methacrylate, worked rubber; the

resin content Ofrubber, and rubber 4 In eithe case the meltingtemperature of the resin is lowered by exemplified by. chlorinatedrubber; making such addition'to the essential composition when highlyelastic coatings are desired.

Additions, such as those above noted, may be made to our essentialcomposition without departure from our invention, and while remainingwithin the definition of that invention as contained in our appendedclaims.

We claim as our invention:

1. The herein-disclosed thermoplastic coating composition consistingessentially of a homogeneous mixture 01 paraflin wax and thermoplasticand25% to 90% oithewax.

3. The herein-disclosed thermoplastic coating composition consisting ofa homogeneus mixture of parafiin wax and thermoplastic terpene resinmelting higher than the paraffin wax and composed of polymers ofunsaturated pinene constituents of turpentine in' the approximateproportion of 10% to 75% of the terpene polymers and 25% to 90% of thewax.

4. The herein-disclosed thermoplastic coating composition consistinessentially of a homogeneous mixture of a wax and thermoplastic terpeneresin melting higher than the wax and composed of polymers ofunsaturated pinene constituents of turpentine.

5. The herein-disclosed thermoplastic coating composition having as itsmajor component a homogeneous mixture of a wax andthermoplastic terpeneresin melting higher than the wax and composed of polymers ofunsaturated pinene constituents of turpentine.

FRANK w. CORKERY. v SAMUEL G. BURRQUGHS.

